The invention relates to improvements in apparatus for singularizing stacked sheets of paper or the like, and more particularly to improvements in apparatus of the type disclosed in the aforementioned commonly owned copending patent application Ser. No. 07/317,724 of Hans Muller.
The Muller application discloses an apparatus wherein a rotor carries a set of rotatably mounted satellites with suction cups which draw successive sheets from a stack adjacent a first portion of the endless path of movement of the satellites with the rotor. The satellites deliver successive sheets to successive grippers of an endless chain conveyor which is adjacent a second portion of the endless path. The movements of the rotor and of the chain conveyor are synchronized so that each gripper which reaches the second portion of the endless path advances in the direction of advancement of the satellites and encounters a sheet-carrying satellite. The grippers of the chain conveyor and/or the satellites are likely to affect the appearance of certain types of sheets if the movements of the grippers are not accurately synchronized with the movements of the satellites.
U.S. Pat. No. 3,602,495 to Hepp discloses a device which is designed to remove sheets from a stack and to transfer the removed sheets to a first belt conveyor which is biased against a rotor for a set of orbiting satellites. The satellites have suction cups which draw successive sheets from a stack and deliver the sheets to a transfer station where the sheets are taken over by the first belt conveyor which cooperates with a second belt conveyor to frictionally engage and entrain the sheets. The direction of movement of the first belt conveyor at the transfer station is counter to the direction of orbital movement of the satellites. Therefore, it is necessary to abruptly accelerate each sheet which reaches the transfer station from the speed of movement with the respective satellite to the speed of movement with the first belt conveyor It has been found that such abrupt acceleration (which necessitates pronounced grasping of sheets by the two belt conveyors) entails the development of stripes, particularly in the region of leaders of the transferred sheets. Furthermore, singularizing apparatus which are designed to abruptly accelerate sheets during transfer from a first transporting unit to another transporting unit are incapable of ensuring uniform spacing of transferred sheets, especially if the sheets are to be transferred at a high or very high frequency which is often necessary in gathering and like machines for signatures and the like.